1. Field of the Invention
The present invention relates to a lens apparatus having an image stabilization function.
2. Description of the Related Art
A conventional image stabilizing apparatus as disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-229089, which is installed in a lens apparatus, detects vibration by using a vibration sensor to control a correction lens for decentering an optical axis according to the detected vibration. As the vibration sensor, an angular velocity sensor that mainly outputs an analog signal is used, and when vibration occurs, the angular velocity sensor detects an angular velocity and outputs an analog signal according to the vibration. The output angular velocity signal is converted into a vibration angle signal by integration, and the calculated vibration angle signal thus is used for calculating a control amount of the correction lens. This control data is used for controlling a driving device such as a motor, to thereby correct an image blur.
Further, there is proposed such an operation that whether or not the lens apparatus is in a pan/tilt operation is automatically determined based on a vibration signal obtained from the vibration sensor, and when it is determined that the lens apparatus is in the pan/tilt operation, the mode of correction for an image blur is switched to an appropriate one. In an example of the proposed operation, when it is determined that the lens apparatus is in the pan/tilt operation, the correction for an image blur is stopped to prevent the screen from becoming unnatural because of the correction for the image blur performed during the pan/tilt operation, and to improve operability of the pan/tilt operation. Whether or not the lens apparatus is in the pan/tilt operation is determined by, for example, detecting whether or not the intensity of the vibration signal obtained from the vibration sensor continues to exceed a predetermined threshold value for a fixed period of time or longer.
However, even during the intended pan/tilt operation, if the displayed image transitions slowly, an image blur due to vibration is noticeable in the displayed image. Therefore, it is desired that the image blur due to vibration is corrected even during the intended pan/tilt operation.
In view of the above, it is conceived that filtering or other such processing is performed to separate a signal component attributed to the vibration from a signal component attributed to the intended pan/tilt operation in the signal output from the vibration detection portion, to thereby correct an image blur based only on the signal component attributed to the vibration targeted for the correction. However, the frequency component of the signal component attributed to the vibration is generally distributed approximately from 0.5 Hz to 30 Hz, and the signal component attributed to the intended pan/tilt operation is also included in this frequency band. Accordingly, it is difficult to completely separate the signal component attributed to the vibration targeted for correction from the signal component attributed to the intended pan/tilt operation.